/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the  "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id$
 */
package wx.xml.xalan.xpath.functions;

import wx.xml.xalan.xalan.templates.Constants;
import wx.xml.xalan.xpath.ExtensionsProvider;
import wx.xml.xalan.xpath.XPathContext;
import wx.xml.xalan.xpath.compiler.FunctionTable;
import wx.xml.xalan.xpath.objects.XBoolean;
import wx.xml.xalan.xpath.objects.XObject;

/**
 * Execute the ExtFunctionAvailable() function.
 *
 * @xsl.usage advanced
 */
public class FuncExtFunctionAvailable extends FunctionOneArg {
    static final long serialVersionUID = 5118814314918592241L;

    transient private FunctionTable m_functionTable = null;

    /**
     * Execute the function.  The function must return
     * a valid object.
     *
     * @param xctxt The current execution context.
     * @return A valid XObject.
     * @throws javax.xml.transform.TransformerException
     */
    public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException {

        String prefix;
        String namespace;
        String methName;

        String fullName     = m_arg0.execute(xctxt).str();
        int    indexOfNSSep = fullName.indexOf(':');

        if (indexOfNSSep < 0) {
            prefix = "";
            namespace = Constants.S_XSLNAMESPACEURL;
            methName = fullName;
        } else {
            prefix = fullName.substring(0, indexOfNSSep);
            namespace = xctxt.getNamespaceContext().getNamespaceForPrefix(prefix);
            if (null == namespace)
                return XBoolean.S_FALSE;
            methName = fullName.substring(indexOfNSSep + 1);
        }

        if (namespace.equals(Constants.S_XSLNAMESPACEURL)) {
            try {
                if (null == m_functionTable)
                    m_functionTable = new FunctionTable();
                return m_functionTable.functionAvailable(methName) ? XBoolean.S_TRUE : XBoolean.S_FALSE;
            } catch (Exception e) {
                return XBoolean.S_FALSE;
            }
        } else {
            //dml
            ExtensionsProvider extProvider = (ExtensionsProvider) xctxt.getOwnerObject();
            return extProvider.functionAvailable(namespace, methName)
                   ? XBoolean.S_TRUE : XBoolean.S_FALSE;
        }
    }

    /**
     * The function table is an instance field. In order to access this instance
     * field during evaluation, this method is called at compilation time to
     * insert function table information for later usage. It should only be used
     * during compiling of XPath expressions.
     *
     * @param aTable an instance of the function table
     */
    public void setFunctionTable(FunctionTable aTable) {
        m_functionTable = aTable;
    }
}
